A2 Respiration test Total marks [40].

Similar presentations

2 The diagram below shows some of the stages in glycolysis:GlucoseHexose phosphateHexose biphosphateTriose phosphatePyruvateXYZReduced ZState precisely where this process occurs ………………………………………[1]Identify substance X ……………………………………………..…………………[1]Identify substance Y ………………………………………………………………..[1]Briefly outline the fate of substance ‘reduced Z’ …………………………………………………………………………………………………………………….. ……………………………………………………………………………………………..[2]in the cytoplasmATP/phosphate group from ATPhydrogenEnters mitochondria; is (re-)oxidised; in the electron transport chain;

3 Carefully read the following account of aerobic respiration and then fill in the blanks:In the first stages of respiration which occurs in the ……………………………………….. of the cell, glucose is ……………………………….. to pyruvic acid. Glycolysis yields ………………………….and a reduced coenzyme.The pyruvic acid then combines with coenzyme A to form …………………………………….. which enters the Kreb’s cycle which occurs in the …………………………………………. of the ………………………………………………..During these reactions hydrogen atoms are removed from a series of intermediate compounds by enzymes called …………………………………… . The hydrogen atoms are passed to carriers such as ……………………………………… .In the third stage of aerobic respiration, the carriers are alternately reduced and …………………….as they gain and lose …………………………. . Energy is released and used to phosphorylate ADP, forming ………………………. . The hydrogen atoms finally combine with……………………….. to form …………………………… [13]cytoplasmoxidisedATPacetyl CoAmatrixmitochondriadehydrogenasesNAD/FADoxidisedelectronsATPoxygenwater

4 Below is a diagram of a mitochondrionAdd labels where indicated. [5]matrixcristaeb) any point on theinner membraneinner membraneouter membraneintermembrane spaceIndicate on the diagram the precise site of the electron transport chain [1]

5 The same amount of ADP was added each time. An experiment was carried out to measure the rate at which a sample of mitochondria used oxygen under different conditions.The mitochondria were placed in a well oxygenated liquid with a water potential equal to the water potential of their contents.At time A, an end-product of glycolysis was added to the liquid. At times B, C and D, ADP was added.The same amount of ADP was added each time.The results of this experiment are shown in the graph below:Time (mins)Oxygen concentration in the liquidABDC

6 ………………………………………………………………………………………………………… [2]a) Explain why the liquid used in the experiment should have the same water potential as the contents of the mitochondria………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… [2]to ensure there is no net movement of water/osmosisthat would cause a dilution/concentration of the matrix contentsor damage to mitochondria/bursting of organelle

7 b) (i) State the name of the substance that was added at A ……………………………………………………………… [1](ii) Name the two stages of the respiratory process that take place in the mitochondria……………………………………………………………………………………………………………………….[2](iii) State the role of oxygen in these respiratory processes……………………………………………………………………………………………………………………..……….[1]pyruvate/pyruvic acidlink reaction; Kreb’s cycle; ETC; oxidative phosphorylationto reoxidise the last substance/last cytochrome in the ETC

8 Oxygen concentration in the liquidc) Explain the result of adding ADP at the following points on the graph;B and C……………………………………………………………………………………………………………………………………………………..… [3]oxidative phosphorylation can occur/ADP converted to ATPwhich requires oxygento react with hydrogen to form waterless occurs at C than B because amount of reduced coenzymes is less/ORATime (mins)Oxygen concentration in the liquidABDC

9 Oxygen concentration in the liquid(ii) D……………………………………………………………………..………[2]no reaction occursdue to lack of reduced NAD/FADwhich means lack of hydrogen ions/electrons for ETCTime (mins)Oxygen concentration in the liquidABDC

10 because glycolysis occurs that requires additional ADP Yeast cells can respire anaerobically using glucose as a substrate.(i) State the end products formed from the glucose if oxygen is not available to the yeast cells……………………………………………………………………………………………………………………………………………………………………………………………… [2](ii) Explain why ADP is required in anaerobic conditions[3]ethanol/ethanalcarbon dioxideto form ATPbecause glycolysis occursthat requires additional ADPto give a net gain of 2 ATP molecules